Traditionally, medications have been administered by various routes including orally, subcutaneously, intramuscularly, or intravenously. Other drug delivery systems include, for example, transdermal patches, membrane encased cells genetically engineered to secrete a desired drug, for example, nerve growth factor or insulin, and slow-release drug systems including for example, NORPLANT.
Traditional routes of administration are problematic in that they require strict patient compliance, i.e., when medication is administered orally, such as an antibiotic, hormone, vitamin, or when repeated visits to the doctor are necessary because the route of administration is by injection. These methods of administration are especially problematic in cases where the patient is a child, is elderly, or where the medication must be administered on a chronic basis, i.e., weekly allergy injections. Compliance with taking medication is a problem for many adults, i.e., they simply forget to take it. Further, weekly allergy injections deter many people from obtaining needed treatment because weekly injections at the doctor's office interferes with their activities or schedules.
Transdermal patches are currently used to administer drugs such as hormones, estrogen, nicotine (NICORETTE to stop smoking), and nitroglycerin (for angina pain). While this system is quite good, a drug must be able to penetrate the skin barrier in order to be administered via a transdermal patch. Many drugs cannot be administered in effective amounts transdermally. Other slow-release delivery systems such as NORPLANT are useful, but they require the removal of the matrix itself after the drug has been completely absorbed over time. Thus, surgery is required to insert the composition and to remove the exhausted matrix from the patient.
The present invention solves the problems presented by the prior art routes, forms and methods of administration by providing an implantable pharmaceutical composition containing the active substance in a biologically-compatible, self-absorbing matrix. Further, the present invention provides an implantation device for implanting the present pharmaceutical composition in the subcutaneous tissue of a patient at a desired site.